US20050134802A1 - Projection device and liquid crystal panel unit for use in the projection device - Google Patents
Projection device and liquid crystal panel unit for use in the projection device Download PDFInfo
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- US20050134802A1 US20050134802A1 US10/742,922 US74292203A US2005134802A1 US 20050134802 A1 US20050134802 A1 US 20050134802A1 US 74292203 A US74292203 A US 74292203A US 2005134802 A1 US2005134802 A1 US 2005134802A1
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- United States
- Prior art keywords
- liquid crystal
- crystal panel
- optical compensation
- rotation
- compensation sheet
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
- H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
- H04N9/3141—Constructional details thereof
- H04N9/315—Modulator illumination systems
- H04N9/3167—Modulator illumination systems for polarizing the light beam
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/005—Projectors using an electronic spatial light modulator but not peculiar thereto
- G03B21/006—Projectors using an electronic spatial light modulator but not peculiar thereto using LCD's
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/145—Housing details, e.g. position adjustments thereof
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
- H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
- H04N9/3102—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators
- H04N9/3105—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators
Definitions
- the present invention relates to projection devices in which an optical compensation sheet is arranged between a liquid crystal panel and a light polarizing plate.
- FIGS. 8 ( a ) and 8 ( b ) are exploded oblique views of a liquid crystal panel 7 and light polarizing plates 73 and 74 that sandwich the liquid crystal panel 7 .
- FIG. 8 ( a ) shows a state in which no electric field is applied across the liquid crystal panel 7
- FIG. 8 ( b ) shows a state in which an electric field is applied across the liquid crystal panel 7 .
- each of the polarizing plates 73 and 74 allows the passage of only one of two polarized light components perpendicular to each other, and the polarizing plates 73 and 74 are arranged so that the oscillation planes of the polarized light components that are allowed to pass through them are 90 degrees apart from each other.
- the oscillation planes of the polarizing plates 73 and 74 must be exactly 90 degrees apart.
- a configuration is known in which the polarizing plates 73 and 74 are rotationally adjusted within a plane perpendicular to the optical axis of the liquid crystal panel 7 (see Japanese Laid-Open Pat. App. Pub. No. 2000-39591).
- the liquid crystal panel 7 is configured by enclosing liquid crystal molecules 57 between transparent display substrates 70 and 71 .
- the two display substrates 70 and 71 are subjected to a rubbing process, and the rod-like liquid crystal molecules 57 are contained between the two display substrates 70 and 71 with the director of the molecules being twisted.
- the liquid crystal panel 7 is of a so-called normally white type, in which, when no electric field is applied between the display substrates 70 and 71 , the polarized light that has been transmitted through polarizing plate 73 , the incident side, passes through polarizing plate 74 , the output side, with its direction being bent 90 degrees due to the twist of the directors of the liquid crystal molecules 57 , as shown in FIG. 8 ( a ). As a consequence, the liquid crystal panel 7 appears bright, i.e., white.
- the liquid crystal molecules 57 align vertically, and consequently the polarized light that has been transmitted through the incident-side polarizing plate 73 passes through the interstices between the liquid crystal molecules 57 .
- the polarized light is blocked by the output-side polarizing plate 74 , and thus the liquid crystal panel 7 appears black.
- the liquid crystal panel 7 displays an image by switching the presence/absence of the electric field in each of the microspaces.
- optical compensation sheets 8 and 8 a in which liquid crystal molecules 58 are arrayed along the thickness direction between the liquid crystal panel 7 and the incident/output-side polarizing plates 73 and 74 , as shown in FIG. 9 .
- the discotic liquid crystal compound is a chemical compound in which ester molecules are layered with benzene rings serving as cores.
- the tilt angles of the liquid crystal molecules 58 change continuously along the thickness direction of the sheet, and the outermost liquid crystal molecules 58 are arranged substantially horizontally.
- the birefringence of the liquid crystal molecules 57 in the liquid crystal panel 7 is compensated, and thus light leaking from the liquid crystal panel 7 is not transmitted through the polarizing plate 74 . Consequently, black colors can be reproduced completely black on the liquid crystal panel 7 , maximizing the contrast.
- optical compensation sheets 8 and 8 a are attached on to the polarizing plates 73 and 74 in many cases.
- the alignment orientation of the liquid crystal molecules 58 in the optical compensation sheets 8 and 8 a needs to be parallel to the orientation of the display substrates 70 and 71 .
- optical compensation sheets 8 and 8 a should be attached on to the polarizing plates 73 and 74 so that the alignment orientation of the liquid crystal molecules 58 is parallel to the orientation of the display substrates 70 and 71 .
- the optical compensation sheets 8 are cut out from a film sheet 85 into a desired dimension, but, as shown in FIG. 10 , there are cases in which the cutting lines accidentally deviate, as indicated by the dotted lines, from the proper position.
- the alignment orientation of the liquid crystal molecules 58 deviate from the originally intended orientation.
- light that must be blocked is allowed to pass through. Consequently, partial leakage of light occurs, into an area is essentially supposed to display black, causing display patchiness.
- the optical compensation sheets 8 are affixed to the polarizing plates 73 and 74 , if contrast reduction or display patchiness occurs it has been necessary to replace the optical compensation sheets 8 with different optical compensation sheets 8 having different optical axes. This makes it necessary to stock a variety of optical compensation sheets 8 having various optical axes, inviting adverse consequences such incidents of unneeded stock.
- the applicant has conceived rotatively adjusting the alignment orientation of the liquid crystal molecules 58 in the optical compensation sheet 8 within a plane orthogonal to the optical axis to project uniform images having distinct contrast between black and white colors.
- the present invention provides a projection device comprising: a liquid crystal panel 7 enclosing liquid crystal molecules 57 , the liquid crystal panel for irradiation with light from a light source 35 ; a polarizing plate 73 opposing the liquid crystal panel; and an optical compensation sheet 8 arranged between the liquid crystal panel 7 and the polarizing plate 73 , for compensating birefringence of the liquid crystal molecules 57 ; wherein the optical compensation sheet 8 is attached to a rotational adjusting mechanism 1 provided on a chassis 3 so as to be rotatively adjustable within a plane perpendicular to an optical axis L.
- the rotational adjusting mechanism 1 comprises a first rotation plate 2 on which the optical compensation sheet 8 is fitted, and a second rotation plate 6 on which the polarizing plate 73 is fitted, the rotation plates 2 and 6 being spaced apart from and opposing one another; and a guide shaft 60 protruding from one of the rotation plates for fitting into a slit 20 opening in the other rotation plate, so that the rotation plates can be rotatively adjusted independently of one another.
- the alignment orientation of the liquid crystal molecules 58 in the optical compensation sheet 8 can be set precisely parallel to the alignment orientation of the liquid crystal panel 7 . This makes it possible to project uniform images having a sharp contrast between black and white colors.
- first rotation plate 2 and the second rotation plate 6 that make up the rotational adjusting mechanism 1 are adjusted independently of one another means that the adjustment to one of the rotation plates does not cause displacement of the other one of rotation plates, ensuring stability in the adjustment.
- FIG. 1 is a plan view of a projection device
- FIG. 2 is an enlarged plan view of a periphery of a liquid crystal panel for green
- FIG. 3 is an exploded oblique view of a rotational adjusting mechanism to which an incident-side polarization plate and an incident-side optical compensation sheet are attached;
- FIGS. 4 ( a ), 4 ( b ), and 4 ( c ) are plan views showing an adjustment operation
- FIG. 5 is a cross-sectional view showing a first rotation plate fitted into a groove, viewed in the direction B in FIG. 3 ;
- FIGS. 6 ( a ) and 6 ( b ) are front views showing the rotating state of a second rotation plate and the rotating state of the first rotation plate, respectively;
- FIG. 7 is a front view of a screen
- FIGS. 8 ( a ) and 8 ( b ) are exploded oblique views of a liquid crystal panel and polarizing plates, FIG. 8 ( a ) showing the state in which no electric field is applied across the liquid crystal panel and FIG. 8 ( b ) showing the state in which an electric field is applied across the liquid crystal panel;
- FIG. 9 is a front view of the liquid crystal panel of FIG. 8 , viewed from the direction A in FIG. 8 , on which optical compensation sheets are attached;
- FIG. 10 is a view showing how optical compensation sheets are cut out from a film sheet.
- FIG. 1 is a plan view showing a projection device pertaining to the present example.
- the device is furnished with three liquid crystal panels 7 , 7 a , and 7 b corresponding to three primary colors of light, red (R), green (G), and blue (B), on a chassis 3 .
- These panels are irradiated with intense light emanating from a light source 35 , and the light rays transmitted through the liquid crystal panels are combined to project images on a screen.
- a feature of the present example lies in rotation-adjustment of an optical compensation sheet 8 , the overall configuration is described first.
- the liquid crystal panels 7 a and 7 b corresponding to red and blue, respectively, are arranged opposing each other with the optical axis of a projection lens 36 interposed therebetween, and a prism body 30 is arranged between the liquid crystal panels 7 a and 7 b .
- the liquid crystal panel 7 corresponding to green is provided on the opposite side from the projection lens 36 with the prism body 30 interposed therebetween.
- a light source 35 is arranged at the entrance of the light path to the chassis 3 , and on the light path, total reflection mirrors 75 , 76 , 77 , and 78 as well as dichroic mirrors 45 and 46 are arranged, all of which are tilted with respect to the light path.
- the light emanating from the light source 35 is reflected by the total reflection mirror 75 .
- the dichroic mirror 45 allows the red component to be transmitted therethrough, while it reflects green and blue components.
- the red component is reflected by the total reflection mirror 76 , is projected on to the liquid crystal panel 7 a corresponding to red, and is directed toward the projection lens 36 by the prism body 30 .
- the green component reflects off the dichroic mirror 46 and is incident on the prism body 30 , and the incident light passes through the prism body 30 , entering the projection lens 36 .
- the blue component is reflected by the total reflection mirror 77 , traveling through a relay lens 38 , and is then reflected by a complex mirror 31 in the prism body 30 , entering the projection lens 36 , so that it is projected on to a screen 37 .
- FIG. 2 is an enlarged plan view showing the liquid crystal panel 7 corresponding to green and its periphery. It should be noted that the peripheries of respective liquid crystal panels 7 a and 7 b corresponding to red and blue also have a similar configuration to the periphery of the liquid crystal panel 7 corresponding to green, but only the liquid crystal panel 7 corresponding to green is illustrated for the sake of convenience in explanation.
- Respective polarizing plates 73 and 74 are arranged on the incident side and output side of the liquid crystal panel 7 .
- one component of the polarized light that has been transmitted through the incident-side polarizing plate 73 (assumed to be p-wave) is twisted in the liquid crystal panel 7 so that the polarization angle is changed to be s-wave that is perpendicular to the p-wave, and is transmitted through the output-side polarizing plate 74 .
- An incident-side optical compensation sheet 8 is arranged between the liquid crystal panel 7 and the incident-side polarization plate 73 , while an output-side optical compensation sheet 8 a is arranged between the liquid crystal panel 7 and the output-side polarization plate 74 .
- the incident-side polarization plate 73 and the incident-side optical compensation sheet 8 , and the output-side polarization plate 74 and the output-side optical compensation sheet 8 a are attached to respective rotational adjusting mechanisms 1 , 1 so that they can be rotatively adjusted within a plane perpendicular to an optical axis L.
- FIG. 3 is an exploded oblique view showing an rotational adjusting mechanism 1 to which the incident-side polarization plate 73 and the incident-side optical compensation sheet 8 are attached. It should be noted that the output-side polarization plate 74 and the output-side optical compensation sheet 8 a are also attached to a rotational adjusting mechanism 1 having the same configuration.
- the rotational adjusting mechanism 1 is furnished with a first rotation plate 2 affixed to a thin glass plate (not shown), to which the optical compensation sheet 8 is to be attached, and a second rotation plate 6 , to which the polarizing plate 73 is to be attached. As will be described later, the two rotation plates 2 and 6 are rotatively adjusted independently of one another.
- the rotational adjusting mechanism 1 is mounted onto a wall piece 4 erected from the chassis 3 .
- the first rotation plate 2 has a through opening 21 in which the optical compensation sheet 8 is fitted substantially at the center with respect to its height, and two arc-shaped slits 20 , 20 in its upper end portion.
- One ends of the arc-shaped slits 20 , 20 have expanded portions 20 a , 20 a that are formed to be larger in the vertical width than the arc-shaped slits 20 , 20 .
- the first protruding plate 23 has a first long slit 24 extending horizontally.
- the right end of the first rotation plate 2 extends upward, forming a knob 25 to be operated by the finger of an adjusting operator.
- the second rotation plate 6 has a through opening 61 in which the polarizing plate 73 is attached, opened at substantially the center with respect to its height, and two guide shafts 60 , 60 protrude from the upper end area thereof toward the first rotation plate 2 .
- Two notches 62 , 62 are opened in the lower end of the second rotation plate 6 . From an area on the second rotation plate 6 that is below the through opening 61 , a rotation-support shaft 63 protrudes toward the first rotation plate 2 .
- the guide shafts 60 , 60 and the rotation-support shaft 63 have grooves 67 , 67 , 67 formed therearound.
- the first rotation plate 2 is fitted in such a manner that the guide shafts 60 , 60 are inserted into the expanded portions 20 a , and thereafter, the peripheral edges of the arc-shaped slits 20 , 20 are fitted to the grooves 67 , 67 (see FIG. 5 ).
- the notch 22 of the first rotation plate 2 fits in the groove 67 of the rotation-support shaft 63 .
- the distance between the first rotation plate 2 and the second rotation plate 6 is kept to be invariable.
- the second protruding plate 64 has a second long slit 65 and two third long slits 66 , 66 opened therein.
- the right end of the second rotation plate 6 extends upward, forming a knob 68 to be operated by the finger of an adjusting operator.
- the first rotation plate 2 rotates around the rotation-support shaft 63 within a plane perpendicular to the optical axis L, and the rotation is guided by the arc-shaped slits 20 , 20 being fitted to the guide shafts 60 , 60 .
- the first protruding plate 23 overlaps with the second protruding plate 64
- the first long slit 24 overlaps with the second long slit 65 .
- the wall piece 4 has a through opening 44 through which light passes, opened at the center with respect to its height, and the upper end surface thereof is provided with protruding shafts 40 , 40 and a screw hole 41 .
- Mounting protuberances 42 , 42 protrude from the lower end portion of the wall piece 4 , and a recessed groove 43 is formed below the mounting protuberances 42 , 42 on the chassis 3 .
- the lower end of the second rotation plate 6 fits into the recessed groove 43 .
- the mounting protuberances 42 , 42 fit into the notches 62 , 62 of the second rotation plate 6 , so that the second rotation plate 6 rotates around either one of the mounting protuberances 42 , 42 within a plane perpendicular to the optical axis L.
- Gaps are provided laterally between each of the mounting protuberances 42 and the notches 62 , permitting the second rotation plate 6 to rotate.
- the protruding shafts 40 , 40 fit into the third long slits 66 , 66 of the second rotation plate 6 , guiding the rotation of the second rotation plate 6 .
- FIG. 4 ( a ), 4 ( b ), and 4 ( c ) are plan views showing adjustment operations
- FIG. 6 ( a ) and 6 ( b ) are front views respectively showing how the second rotation plate and the first rotation plate rotate.
- a set screw 26 is passed through both the long slits 24 and 65 from above and is screwed into a screw hole 41 in the wall piece 4 .
- the second rotation plate 6 is rotated.
- the set screw 26 is loosened, the knob 68 of the second rotation plate 6 is held with the fingers from above, and as shown in FIG. 4 ( b ), the second rotation plate 6 is moved to the right. Of course, it may be moved to the left.
- the notches 62 , 62 are fitted onto the mounting protuberances 42 , 42 as shown in FIG. 3
- the second rotation plate 6 rotates around the contact points of the mounting protuberances 42 , 42 and the peripheral edges of the notches 62 , 62 within a plane perpendicular to the optical axis L, as shown in FIG. 6 ( a ).
- the first rotation plate 2 does not rotate.
- the set screw 26 is tightened.
- the first rotation plate 2 is rotated.
- the set screw 26 is loosened, a knob 25 of the first rotation plate 2 is held with the fingers from above, and as shown in FIG. 4 ( c ), the second rotation plate 6 is moved to the right. Of course, it may be moved to the left.
- the notch 22 is fitted onto the rotation-support shaft 63 as shown in FIG. 3 , as shown in FIG. 6 ( b ), the first rotation plate 2 rotates around the rotation-support shaft 63 within a plane perpendicular to the optical axis L. At this time, the second rotation plate 6 does not rotate.
- the set screw 26 is tightened.
- the first rotation plate 2 and the second rotation plate 6 move separately, and they do not operate inter-connectedly.
- the rotation plates 2 and 6 are accessed for the adjustment from above. This makes the adjusting operation stable and easy. It should be noted that the adjustment may be carried out with a jig (not shown) inserted from above the rotation plates 2 and 6 .
- the optical compensation sheet 8 is rotatively adjusted within a plane perpendicular to the optical axis L, and therefore, the alignment orientation of the liquid crystal molecules 58 in the optical compensation sheet 8 can be set precisely parallel to the alignment orientation of the liquid crystal panel 7 . Consequently, it becomes possible to project uniform images having a sharp contrast between black and white colors. Moreover, unlike conventional cases, it is unnecessary to have a variety of optical compensation sheets 8 having various optic axes in stock, eliminating the problem of excess in stock or the like.
- the light source 35 is turned on to display an image on the screen 37 through the projection lens 36 , and the optical compensation sheet 8 and the polarizing plate 73 are adjusted by rotating the rotation plates 2 and 6 so that the contrast between black and white colors becomes sharp.
- the applicant has confirmed the effect of the present invention by obtaining the contrast ratio between black and white colors after rotatively adjusting the optical compensation sheets 8 and 8 a and the polarizing plates 73 and 74 .
- the light source 35 was turned on, but no electric field was applied across the liquid crystal panel 7 to display a white color on the screen 37 .
- the screen area of the screen 37 was divided into nine areas, and the illuminance of the center of each of the divided screen areas was measured.
- the mean value of the illuminances (unit: lux) of the nine screen areas was obtained, and the mean value thus obtained is called “Wave.”
- an electric field is applied across the liquid crystal panel 7 to display a black color on the screen 37 .
- the screen area of the screen 37 is divided into nine areas, and the illuminance of the center of each of the divided screen areas was measured.
- the mean value of the illuminances of the nine screen areas was obtained, and the mean value thus obtained is called “BRave.”
- the ratio of Wave and BRave thus obtained was about 800:1.
- the ratio of Wave and BRave was about 400:1. This proves that the contrast between black and white colors was improved.
- the incident side and the output side of the liquid crystal panel 7 are provided with the optical compensation sheets 8 and 8 a , respectively, but only one of the incident side or the output side may be provided with the optical compensation sheet.
- the rotational adjusting mechanism of the optical compensation sheet 8 is not limited to the configuration shown in FIG. 3 .
- the guide shafts 60 , 60 protrude from the second rotation plate 6 , and the arc-shaped slits 20 , 20 are formed in the first rotation plate 2 ; however, the guide shafts 60 , 60 may protrude from the first rotation plate 2 , and the arc-shaped slits 20 , 20 may be formed in the second rotation plate 6 .
- the configuration of the present invention may be applied to a so-called normally black liquid crystal panel 7 , which appears black when no electric field is applied thereto.
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Abstract
Description
- 1. Field of the Invention
- The present invention relates to projection devices in which an optical compensation sheet is arranged between a liquid crystal panel and a light polarizing plate.
- 2. Description of Related Art
- FIGS. 8(a) and 8(b) are exploded oblique views of a
liquid crystal panel 7 and light polarizingplates liquid crystal panel 7.FIG. 8 (a) shows a state in which no electric field is applied across theliquid crystal panel 7, whereasFIG. 8 (b) shows a state in which an electric field is applied across theliquid crystal panel 7. As is well-known, each of the polarizingplates plates plates plates - The
liquid crystal panel 7 is configured by enclosingliquid crystal molecules 57 betweentransparent display substrates display substrates liquid crystal molecules 57 are contained between the twodisplay substrates - The
liquid crystal panel 7 is of a so-called normally white type, in which, when no electric field is applied between thedisplay substrates plate 73, the incident side, passes through polarizingplate 74, the output side, with its direction being bent 90 degrees due to the twist of the directors of theliquid crystal molecules 57, as shown inFIG. 8 (a). As a consequence, theliquid crystal panel 7 appears bright, i.e., white. - As shown in
FIG. 8 (b), when an electric field is applied between thedisplay substrates liquid crystal molecules 57 align vertically, and consequently the polarized light that has been transmitted through the incident-side polarizingplate 73 passes through the interstices between theliquid crystal molecules 57. The polarized light is blocked by the output-side polarizingplate 74, and thus theliquid crystal panel 7 appears black. Theliquid crystal panel 7 displays an image by switching the presence/absence of the electric field in each of the microspaces. - It is known that in practice, however, in the
liquid crystal panel 7, when an electric field is applied between thedisplay substrates liquid crystal molecules 57 continuously change along the thickness direction of theliquid crystal panel 7, as shown inFIG. 9 . As a consequence, when an electric field is applied between thedisplay substrates liquid crystal molecules 57 in the vicinity of thesubstrates - In recent years, there has been a demand for greater image resolution. The devices that display such high-resolution images are required to maximize the contrast between black color and white color in projected images and project images clearly. If due to the birefringence of the
liquid crystal molecules 57 just mentioned, the polarized light that should be blocked is transmitted through theliquid crystal panel 7 as indicated by the dot-dashed line inFIG. 8 (b), black colors are not completely displayed black. Herein, “birefringence” indicates that the speed at which light propagates differs depending on the orientation of the plane in which it oscillates, and the orientation in which the speed is fast will be referred to as the “fast axis,” whereas the direction in which the speed is slow will be referred to as the “slow axis.” - In view of this, it has been suggested to provide
optical compensation sheets liquid crystal molecules 58 are arrayed along the thickness direction between theliquid crystal panel 7 and the incident/output-side polarizingplates FIG. 9 . - These are transparent sheets in which approximately disk-shaped
liquid crystal molecules 58 composed of a discotic liquid crystal compound are aligned. The discotic liquid crystal compound is a chemical compound in which ester molecules are layered with benzene rings serving as cores. - The tilt angles of the
liquid crystal molecules 58 change continuously along the thickness direction of the sheet, and the outermostliquid crystal molecules 58 are arranged substantially horizontally. As a result, the birefringence of theliquid crystal molecules 57 in theliquid crystal panel 7 is compensated, and thus light leaking from theliquid crystal panel 7 is not transmitted through the polarizingplate 74. Consequently, black colors can be reproduced completely black on theliquid crystal panel 7, maximizing the contrast. - These
optical compensation sheets plates liquid crystal molecules 58 in theoptical compensation sheets display substrates - The applicant, however, has found the following problems.
- The
optical compensation sheets plates liquid crystal molecules 58 is parallel to the orientation of thedisplay substrates - Nevertheless, there are cases in which the alignment orientation of the
liquid crystal molecules 58 in theoptical compensation sheets optical compensation sheets plates - What is more, the
optical compensation sheets 8 are cut out from afilm sheet 85 into a desired dimension, but, as shown inFIG. 10 , there are cases in which the cutting lines accidentally deviate, as indicated by the dotted lines, from the proper position. - In the
optical compensations sheets 8 thus produced, the alignment orientation of theliquid crystal molecules 58 deviate from the originally intended orientation. As a result, light that must be blocked is allowed to pass through. Consequently, partial leakage of light occurs, into an area is essentially supposed to display black, causing display patchiness. Furthermore, since theoptical compensation sheets 8 are affixed to the polarizingplates optical compensation sheets 8 with differentoptical compensation sheets 8 having different optical axes. This makes it necessary to stock a variety ofoptical compensation sheets 8 having various optical axes, inviting adverse consequences such incidents of unneeded stock. - The applicant has conceived rotatively adjusting the alignment orientation of the
liquid crystal molecules 58 in theoptical compensation sheet 8 within a plane orthogonal to the optical axis to project uniform images having distinct contrast between black and white colors. - It is therefore an object of the present invention to provide a projection device furnished with an
optical compensation sheet 8 that is capable of projecting uniform images having a sharp contrast between black and white colors. - The present invention provides a projection device comprising: a
liquid crystal panel 7 enclosingliquid crystal molecules 57, the liquid crystal panel for irradiation with light from alight source 35; a polarizingplate 73 opposing the liquid crystal panel; and anoptical compensation sheet 8 arranged between theliquid crystal panel 7 and the polarizingplate 73, for compensating birefringence of theliquid crystal molecules 57; wherein theoptical compensation sheet 8 is attached to arotational adjusting mechanism 1 provided on a chassis 3 so as to be rotatively adjustable within a plane perpendicular to an optical axis L. - The
rotational adjusting mechanism 1 comprises afirst rotation plate 2 on which theoptical compensation sheet 8 is fitted, and asecond rotation plate 6 on which the polarizingplate 73 is fitted, therotation plates guide shaft 60 protruding from one of the rotation plates for fitting into aslit 20 opening in the other rotation plate, so that the rotation plates can be rotatively adjusted independently of one another. - Because the
optical compensation sheet 8 is rotatively adjusted within a plane perpendicular to the optical axis L, the alignment orientation of theliquid crystal molecules 58 in theoptical compensation sheet 8 can be set precisely parallel to the alignment orientation of theliquid crystal panel 7. This makes it possible to project uniform images having a sharp contrast between black and white colors. - In addition, the fact that the
first rotation plate 2 and thesecond rotation plate 6 that make up therotational adjusting mechanism 1 are adjusted independently of one another means that the adjustment to one of the rotation plates does not cause displacement of the other one of rotation plates, ensuring stability in the adjustment. -
FIG. 1 is a plan view of a projection device; -
FIG. 2 is an enlarged plan view of a periphery of a liquid crystal panel for green; -
FIG. 3 is an exploded oblique view of a rotational adjusting mechanism to which an incident-side polarization plate and an incident-side optical compensation sheet are attached; - FIGS. 4(a), 4(b), and 4(c) are plan views showing an adjustment operation;
-
FIG. 5 is a cross-sectional view showing a first rotation plate fitted into a groove, viewed in the direction B inFIG. 3 ; - FIGS. 6(a) and 6(b) are front views showing the rotating state of a second rotation plate and the rotating state of the first rotation plate, respectively;
-
FIG. 7 is a front view of a screen; - FIGS. 8(a) and 8(b) are exploded oblique views of a liquid crystal panel and polarizing plates,
FIG. 8 (a) showing the state in which no electric field is applied across the liquid crystal panel andFIG. 8 (b) showing the state in which an electric field is applied across the liquid crystal panel; -
FIG. 9 is a front view of the liquid crystal panel ofFIG. 8 , viewed from the direction A inFIG. 8 , on which optical compensation sheets are attached; and -
FIG. 10 is a view showing how optical compensation sheets are cut out from a film sheet. - With reference to the drawings, one example of the present invention is described in detail below.
-
FIG. 1 is a plan view showing a projection device pertaining to the present example. The device is furnished with threeliquid crystal panels light source 35, and the light rays transmitted through the liquid crystal panels are combined to project images on a screen. Although a feature of the present example lies in rotation-adjustment of anoptical compensation sheet 8, the overall configuration is described first. - In the chassis 3, the
liquid crystal panels projection lens 36 interposed therebetween, and aprism body 30 is arranged between theliquid crystal panels liquid crystal panel 7 corresponding to green is provided on the opposite side from theprojection lens 36 with theprism body 30 interposed therebetween. - A
light source 35 is arranged at the entrance of the light path to the chassis 3, and on the light path, total reflection mirrors 75, 76, 77, and 78 as well asdichroic mirrors - The light emanating from the
light source 35 is reflected by thetotal reflection mirror 75. Thereafter, thedichroic mirror 45 allows the red component to be transmitted therethrough, while it reflects green and blue components. Then, the red component is reflected by thetotal reflection mirror 76, is projected on to theliquid crystal panel 7 a corresponding to red, and is directed toward theprojection lens 36 by theprism body 30. The green component reflects off thedichroic mirror 46 and is incident on theprism body 30, and the incident light passes through theprism body 30, entering theprojection lens 36. The blue component is reflected by thetotal reflection mirror 77, traveling through arelay lens 38, and is then reflected by acomplex mirror 31 in theprism body 30, entering theprojection lens 36, so that it is projected on to ascreen 37. -
FIG. 2 is an enlarged plan view showing theliquid crystal panel 7 corresponding to green and its periphery. It should be noted that the peripheries of respectiveliquid crystal panels liquid crystal panel 7 corresponding to green, but only theliquid crystal panel 7 corresponding to green is illustrated for the sake of convenience in explanation. - Respective
polarizing plates liquid crystal panel 7. As is well-known, when no electric field is applied across theliquid crystal panel 7, one component of the polarized light that has been transmitted through the incident-side polarizing plate 73 (assumed to be p-wave) is twisted in theliquid crystal panel 7 so that the polarization angle is changed to be s-wave that is perpendicular to the p-wave, and is transmitted through the output-sidepolarizing plate 74. - An incident-side
optical compensation sheet 8 is arranged between theliquid crystal panel 7 and the incident-side polarization plate 73, while an output-sideoptical compensation sheet 8 a is arranged between theliquid crystal panel 7 and the output-side polarization plate 74. - The incident-
side polarization plate 73 and the incident-sideoptical compensation sheet 8, and the output-side polarization plate 74 and the output-sideoptical compensation sheet 8 a are attached to respectiverotational adjusting mechanisms -
FIG. 3 is an exploded oblique view showing anrotational adjusting mechanism 1 to which the incident-side polarization plate 73 and the incident-sideoptical compensation sheet 8 are attached. It should be noted that the output-side polarization plate 74 and the output-sideoptical compensation sheet 8 a are also attached to arotational adjusting mechanism 1 having the same configuration. - The
rotational adjusting mechanism 1 is furnished with afirst rotation plate 2 affixed to a thin glass plate (not shown), to which theoptical compensation sheet 8 is to be attached, and asecond rotation plate 6, to which thepolarizing plate 73 is to be attached. As will be described later, the tworotation plates rotational adjusting mechanism 1 is mounted onto awall piece 4 erected from the chassis 3. - The
first rotation plate 2 has a throughopening 21 in which theoptical compensation sheet 8 is fitted substantially at the center with respect to its height, and two arc-shapedslits slits portions slits - Provided in the lower end of the
first rotation plate 2 is anotch 22. A first protrudingplate 23 bulging upwardly in a substantially arc shape protrudes from above the arc-shapedslits first rotation plate 2 toward thewall piece 4. The first protrudingplate 23 has a firstlong slit 24 extending horizontally. The right end of thefirst rotation plate 2 extends upward, forming aknob 25 to be operated by the finger of an adjusting operator. - The
second rotation plate 6 has a throughopening 61 in which thepolarizing plate 73 is attached, opened at substantially the center with respect to its height, and twoguide shafts first rotation plate 2. Twonotches second rotation plate 6. From an area on thesecond rotation plate 6 that is below the throughopening 61, a rotation-support shaft 63 protrudes toward thefirst rotation plate 2. - The
guide shafts support shaft 63 havegrooves first rotation plate 2 is fitted in such a manner that theguide shafts portions 20 a, and thereafter, the peripheral edges of the arc-shapedslits grooves 67, 67 (seeFIG. 5 ). Thenotch 22 of thefirst rotation plate 2 fits in thegroove 67 of the rotation-support shaft 63. Thus, the distance between thefirst rotation plate 2 and thesecond rotation plate 6 is kept to be invariable. - A second protruding
plate 64 bulging upwardly in an arc shape protrudes from above theguide shafts second rotation plate 6 toward thewall piece 4. The second protrudingplate 64 has a secondlong slit 65 and two thirdlong slits second rotation plate 6 extends upward, forming aknob 68 to be operated by the finger of an adjusting operator. - The
first rotation plate 2 rotates around the rotation-support shaft 63 within a plane perpendicular to the optical axis L, and the rotation is guided by the arc-shapedslits guide shafts plate 23 overlaps with the second protrudingplate 64, and the firstlong slit 24 overlaps with the secondlong slit 65. - The
wall piece 4 has a through opening 44 through which light passes, opened at the center with respect to its height, and the upper end surface thereof is provided with protrudingshafts screw hole 41. Mountingprotuberances wall piece 4, and a recessedgroove 43 is formed below the mountingprotuberances second rotation plate 6 fits into the recessedgroove 43. The mountingprotuberances notches second rotation plate 6, so that thesecond rotation plate 6 rotates around either one of the mountingprotuberances - Gaps are provided laterally between each of the mounting
protuberances 42 and thenotches 62, permitting thesecond rotation plate 6 to rotate. The protrudingshafts long slits second rotation plate 6, guiding the rotation of thesecond rotation plate 6. - Rotation-Adjustment of Polarizing Plate
-
FIG. 4 (a), 4(b), and 4(c) are plan views showing adjustment operations, andFIG. 6 (a) and 6(b) are front views respectively showing how the second rotation plate and the first rotation plate rotate. As shown inFIG. 4 (a), with the firstlong slit 24 and the secondlong slit 65 overlapping, aset screw 26 is passed through both thelong slits screw hole 41 in thewall piece 4. - To rotation-adjust the
polarizing plate 73, thesecond rotation plate 6 is rotated. Theset screw 26 is loosened, theknob 68 of thesecond rotation plate 6 is held with the fingers from above, and as shown inFIG. 4 (b), thesecond rotation plate 6 is moved to the right. Of course, it may be moved to the left. Since thenotches protuberances FIG. 3 , thesecond rotation plate 6 rotates around the contact points of the mountingprotuberances notches FIG. 6 (a). At this time, thefirst rotation plate 2 does not rotate. After completing the rotation-adjustment, theset screw 26 is tightened. - Rotation-Adjustment of Optical Compensation Sheet
- To rotation-adjust the
optical compensation sheet 8, thefirst rotation plate 2 is rotated. Theset screw 26 is loosened, aknob 25 of thefirst rotation plate 2 is held with the fingers from above, and as shown inFIG. 4 (c), thesecond rotation plate 6 is moved to the right. Of course, it may be moved to the left. Since thenotch 22 is fitted onto the rotation-support shaft 63 as shown inFIG. 3 , as shown inFIG. 6 (b), thefirst rotation plate 2 rotates around the rotation-support shaft 63 within a plane perpendicular to the optical axis L. At this time, thesecond rotation plate 6 does not rotate. After completing the rotation-adjustment, theset screw 26 is tightened. - As described above, the
first rotation plate 2 and thesecond rotation plate 6 move separately, and they do not operate inter-connectedly. In addition, therotation plates rotation plates - The
optical compensation sheet 8 is rotatively adjusted within a plane perpendicular to the optical axis L, and therefore, the alignment orientation of theliquid crystal molecules 58 in theoptical compensation sheet 8 can be set precisely parallel to the alignment orientation of theliquid crystal panel 7. Consequently, it becomes possible to project uniform images having a sharp contrast between black and white colors. Moreover, unlike conventional cases, it is unnecessary to have a variety ofoptical compensation sheets 8 having various optic axes in stock, eliminating the problem of excess in stock or the like. - In rotatively adjusting the
optical compensation sheet 8, thelight source 35 is turned on to display an image on thescreen 37 through theprojection lens 36, and theoptical compensation sheet 8 and thepolarizing plate 73 are adjusted by rotating therotation plates - The applicant has confirmed the effect of the present invention by obtaining the contrast ratio between black and white colors after rotatively adjusting the
optical compensation sheets polarizing plates light source 35 was turned on, but no electric field was applied across theliquid crystal panel 7 to display a white color on thescreen 37. As shown inFIG. 7 , the screen area of thescreen 37 was divided into nine areas, and the illuminance of the center of each of the divided screen areas was measured. The mean value of the illuminances (unit: lux) of the nine screen areas was obtained, and the mean value thus obtained is called “Wave.” - Next, an electric field is applied across the
liquid crystal panel 7 to display a black color on thescreen 37. In a like manner as the foregoing, the screen area of thescreen 37 is divided into nine areas, and the illuminance of the center of each of the divided screen areas was measured. The mean value of the illuminances of the nine screen areas was obtained, and the mean value thus obtained is called “BRave.” - The ratio of Wave and BRave thus obtained was about 800:1. When the
optical compensation sheets liquid crystal panel 7, the ratio of Wave and BRave was about 400:1. This proves that the contrast between black and white colors was improved. - In the foregoing embodiment, the incident side and the output side of the
liquid crystal panel 7 are provided with theoptical compensation sheets - Further, the rotational adjusting mechanism of the
optical compensation sheet 8 is not limited to the configuration shown inFIG. 3 . For example, it is possible to adopt the conventional adjusting mechanism disclosed in Japanese Laid-Open Pat. App. Pub. No. 2000-39591. - In addition, although the foregoing embodiment has described the rotation-adjustment within a plane perpendicular to the optical axis L, a sufficiently advantageous effect can be obtained even for the rotation-adjustment within a plane inclined off the optical axis L.
- In the foregoing embodiment, the
guide shafts second rotation plate 6, and the arc-shapedslits first rotation plate 2; however, theguide shafts first rotation plate 2, and the arc-shapedslits second rotation plate 6. Moreover, the configuration of the present invention may be applied to a so-called normally blackliquid crystal panel 7, which appears black when no electric field is applied thereto. - Only selected embodiments have been chosen to illustrate the present invention. To those skilled in the art, however, it will be apparent from the foregoing disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. Furthermore, the foregoing description of the embodiments according to the present invention is provided for illustration only, and not for limiting the invention as defined by the appended claims and their equivalents.
Claims (5)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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JP2002371510A JP3733112B2 (en) | 2002-12-24 | 2002-12-24 | Projection apparatus and liquid crystal panel unit used in the projection apparatus |
Publications (2)
Publication Number | Publication Date |
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US20050134802A1 true US20050134802A1 (en) | 2005-06-23 |
US7097306B2 US7097306B2 (en) | 2006-08-29 |
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US10/742,922 Expired - Lifetime US7097306B2 (en) | 2002-12-24 | 2003-12-23 | Projection device and liquid crystal panel unit for use in the projection device |
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US (1) | US7097306B2 (en) |
JP (1) | JP3733112B2 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
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US20050110962A1 (en) * | 2003-10-16 | 2005-05-26 | Seiko Epson Corporation | Optical component casing, optical device and projector |
US20060209265A1 (en) * | 2005-03-17 | 2006-09-21 | Seiko Epson Corporation | Prism structure and projector |
US20070258249A1 (en) * | 2006-05-02 | 2007-11-08 | Sanyo Electric Co., Ltd. | Projector device |
US20080316396A1 (en) * | 2007-06-20 | 2008-12-25 | Ryoko Horikoshi | Liquid crystal display apparatus |
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EP1665812A2 (en) * | 2003-09-18 | 2006-06-07 | Koninklijke Philips Electronics N.V. | Method to position a frame |
JP4225954B2 (en) | 2004-07-26 | 2009-02-18 | 三洋電機株式会社 | Projection device and liquid crystal panel unit used in projection device |
JP4839623B2 (en) * | 2005-02-02 | 2011-12-21 | 株式会社日立製作所 | Projection-type image display device |
JP4190529B2 (en) * | 2005-09-09 | 2008-12-03 | 三洋電機株式会社 | Projector device |
JP4190546B2 (en) | 2006-05-02 | 2008-12-03 | 三洋電機株式会社 | LCD projector |
JP2008089626A (en) | 2006-09-29 | 2008-04-17 | Seiko Epson Corp | Liquid crystal device and electronic equipment |
JP2008268264A (en) * | 2007-04-16 | 2008-11-06 | Sanyo Electric Co Ltd | Liquid crystal display device |
JP4703678B2 (en) * | 2008-04-09 | 2011-06-15 | 三洋電機株式会社 | Projector device |
JP2008217028A (en) * | 2008-04-09 | 2008-09-18 | Sanyo Electric Co Ltd | Projector and liquid crystal panel unit to be used for the same |
JP5115365B2 (en) * | 2008-07-04 | 2013-01-09 | セイコーエプソン株式会社 | Optical device and projector |
JP5162625B2 (en) * | 2010-05-25 | 2013-03-13 | 三洋電機株式会社 | Projection device and liquid crystal panel unit used in projection device |
JP5760185B2 (en) * | 2011-05-13 | 2015-08-05 | パナソニックIpマネジメント株式会社 | lighting equipment |
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JP3454719B2 (en) | 1998-07-23 | 2003-10-06 | 三洋電機株式会社 | Projection device with polarizing plate |
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- 2002-12-24 JP JP2002371510A patent/JP3733112B2/en not_active Expired - Fee Related
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US6473180B2 (en) * | 1997-12-02 | 2002-10-29 | Nec Corporation | Measuring method of liquid crystal pretilt angle and measuring equipment of liquid crystal pretilt angle |
US6243065B1 (en) * | 1998-10-29 | 2001-06-05 | Agilent Technologies, Inc. | Reflective ferroelectric liquid crystal light valve with increased light throughput |
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US20050110962A1 (en) * | 2003-10-16 | 2005-05-26 | Seiko Epson Corporation | Optical component casing, optical device and projector |
US7086745B2 (en) * | 2003-10-16 | 2006-08-08 | Seiko Epson Corporation | Optical component casing, optical device and projector |
US20060209265A1 (en) * | 2005-03-17 | 2006-09-21 | Seiko Epson Corporation | Prism structure and projector |
US7661823B2 (en) * | 2005-03-17 | 2010-02-16 | Seiko Epson Corporation | Prism structure and projector |
US20070258249A1 (en) * | 2006-05-02 | 2007-11-08 | Sanyo Electric Co., Ltd. | Projector device |
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Also Published As
Publication number | Publication date |
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JP2004205593A (en) | 2004-07-22 |
US7097306B2 (en) | 2006-08-29 |
JP3733112B2 (en) | 2006-01-11 |
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